The thesis interprets development of Ukrainian language lexicon in historical comparative and typological aspects on the material of printed editions of Printing House of Pochayiv monastery of Assumption of ХVІІІ and the first third of ХІХ c. Conditions and ways of fixing lexical elements characteristic for vernacular speech are traced, the repertory of editions (39 in total) containing text in Ukrainian is determined. These are: liturgical books, catechisms, oratorical works and sermons, textbook of theology, divine songs, poetical works, secular editions (books of practical advices etc.). Lexics connected with animate nature and abiocoen, time, space and other characteristics of being as well as lexics characterizing human intelligence, professional activity, way of life, status is analyzed in detail. It is stated that vernacular lexics prevails in all thematic groups, and interconnection between thematic organization of lexics and intensity of influence of vernacular speech as well as literary sources and foreign languages is observed. Thus Church Slavonic influence reveals itself distinctly in lexics, connected with man as biological being, which is conditioned with topics of religious texts that constitute the basis of Ukrainian literary tradition: a man in all manifestations of his life including biological was always at the centre of attention of such literature. It is however important that use of Slavonicisms is almost always stylistically motivated, they usually functionate in parallel with Ukrainian forms. The influence of Polish literary norm appears itself in nomenclature of diseases, botanical nomenclature - a great part of such lexics, showing very many forms for the same notion in dialects, had been chosen to the normative nomenclature under Polish influence, part of these names being adoptions from Polish or from Western Europe languages through the mediation of Polish. Lexics denoting notions of everyday life is almost thoroughly vernacular, because notions of this sphere are fully covered with vocabulary of everyday spoken language. Whereas different typological influences on literary language that cause appearance of two or more semantic duplicates are marked in thematic groups of lexics denoting processes of functioning of human intelligence and psychic. It is explained by insufficient level of development of literary language, which could have given possibility to create full vocabulary in this onomasiological sphere on the basis of its own means. The material of research gives reasons for naming several factors that cause use of lexemes being admittedly beyond vernacular usage. These are: stylistic purpose; high frequency of some lexemes in texts written in foreign languages, being constantly in the field of view of authors and editors; in case of Polish influence - everyday speaking practice as well. Occasionally foreign lexemes are used for infill of semantic lacunas. Whatever the intensity of influence of systems of foreign languages within one or another thematic group was - these influences always had systematic character and could be explained by some intra- or extralingual factors and never transformed in chaotic interference of languages. The results of research confirm on the one hand difference of upper bound of Old Ukrainian literary language tradition on western and eastern lands of Ukraine, since still in the first third of ХІХ c., when there were quite another trends in the Left-bank Ukraine, most editions of Pochayiv remained within old tradition (as well as for example printed editions of under-Austria Ukraine having been appeared thanks to efforts of M. Levytsky, I. Mohylnytsky). On the other hand, as some editions of Pochayiv witness, there were attempts of making more or less radical changes in the structure of literary language in the direction of closing it to the vernacular language still in ХVІІІ c. This trend may be observed most obviously in "Polityka Svitska" (1770), and "Knyzhytsya dla hospodarstva" (1788), to a lesser extent - in different editions of catechisms and sermons. Such changes are accordant to trends of development of literary language in the Eastern Ukraine, but again the vernacular base being a guide for authors is alternative - this is in the first place the speech of south-western dialects speakers. Both factors - continuation of Old Ukrainian literary language tradition and choice of south-western dialect base when being orientated to vernacular language played their roles afterwards. These had been some of the reasons of the fact that West-Ukrainian tradition of literary language became to a certain extent autonomous and differing from the East-Ukrainian one. Key words: lexical system, semantic group of lexics, thematic group of lexics, printing house of Pochayiv, old-printed books, Old Ukrainian literary language, ХVІІІ - the first third of ХІХ c.
